and many more benefits!

Find us on Facebook

GMAT Club Timer Informer

Hi GMATClubber!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

An infi nite sequence of positive integers is called a [#permalink]
13 Feb 2012, 16:14

2

This post receivedKUDOS

1

This post wasBOOKMARKED

00:00

A

B

C

D

E

Difficulty:

55% (hard)

Question Stats:

48%(01:48) correct
52%(00:47) wrong based on 213 sessions

An infi nite sequence of positive integers is called a coprime sequence if no term in the sequence shares a common divisor (except 1) with any other term in the sequence. If S is an in finite sequence of distinct positive integers, is S a coprime sequence?

(1) An infinite number of integers in S are prime.(2) Each term in S has exactly two factors.

Re: An infi nite sequence of positive integers is called a [#permalink]
13 Feb 2012, 18:07

2

This post receivedKUDOS

Expert's post

An infi nite sequence of positive integers is called a coprime sequence if no term in the sequence shares a common divisor (except 1) with any other term in the sequence. If S is an in finite sequence of distinct positive integers, is S a coprime sequence?

Notice that S is an in finite sequence of distinct positive integers.

(1) An infinite number of integers in S are prime --> obviously these primes will be coprime to each other. But we don't know whether the sequence contains some numbers other than primes, and if it does then the sequence won't be coprime (for example the sequence can contain 4 and 6 in addition to these primes). Not Sufficient.

(2) Each term in S has exactly two factors --> each term in S is a prime, so S contains only distinct primes, which will be coprime. Sufficient.

Re: An infi nite sequence of positive integers is called a [#permalink]
08 Feb 2014, 03:38

Nice, nice nice. Fell into trap and chose wrong answer. Statement 1 seems like each number in s is prime but it is not! Statement 2 makes it look like the numbers are not prime but indeed they are! _________________

Click on Kudos if you liked the post!

Practice makes Perfect.

gmatclubot

Re: An infi nite sequence of positive integers is called a
[#permalink]
08 Feb 2014, 03:38